The present invention relates generally to activation switches. More particularly, the present invention relates to activating fire alarm pull stations in environments that tend to be harsh to contact switches. The present invention also relates to preventing accidental tripping of these alarms by the influence of outside elements.
Manually operated fire alarm pull stations have been in existence for a number of years. Their primary function is to allow occupants to initiate a signal in a fire alarm control panel. The panels are strategically located throughout a property in easy to find locations. The frequency of the locations of these devices is driven by the fact that earlier notification of a possible emergency situation usually results in less damage to property as well saving human life.
Once the fire alarm is activated, the fire alarm system alerts a predetermined number of individuals. This usually involves the building occupants, fire brigade or municipal fire department. An alert is sent so that the appropriate individuals coordinate a response to the alarm. For example, in the event of a fire alarm activation, the local municipalities coordinate by sending the nearest available unit to the designated location. The alarm can also result in responses from the local police and ambulance services.
The pull stations have served to act as a quick response to conditions in which response time is critical. Therefore, the pull stations, like all mechanical devices, need to be maintained to ensure their operability.
Pull stations, of the contact switch type, are susceptible to mechanical failure. One of the primary causes of this mechanical failure is due to environmental conditions. For example, the pull stations are located in the outdoors, parking structures, factories, chemical processing plants and oil refineries. These harsh environments cause contaminants to interfere with the operability of the switch mechanism. To ensure the operability of the switch, the device needs to be maintained on a periodic basis.
Periodic maintenance of the pull station requires coordinating with local emergency personnel and/or alarm monitoring companies as to testing or maintenance taking place on the premise. For example, either the alarm system needs to be shut down or the local authorities need to be apprised of the maintenance that is taking place. Either action insures that if the device is accidentally activated during maintenance, emergency personnel will not be summoned to the location preventing the diversion of the emergency personnel from more critical matters.
A parking garage under renovation or maintenance is a good example of how contact switch-based pull stations are susceptible to mechanical failure at a greater rate than usual. Construction environments create a number of airborne contaminants or particles. These particles are moved and circulated through the structure by the movement of the automobiles and construction equipment. Some of this debris works its way into the fire alarm pull station. The debris begins to pile on the contacts in the switch. After certain coverage of the debris on the switch occurs, the switch ceases to function in that it is not able to make electrical contact. Failure of the switch causes a greater period of time to be added to the response time of the emergency personnel. Furthermore, the activator of the pull station might be led into a false sense of security in that the switch is activated and the appropriate personnel have been alerted.
Accordingly, it is desirable to provide a fire alarm pull station is activated on a non-contact switch basis. Furthermore, it is desirable to provide a non-contact switch, which when subject to conditions or effects could accidentally trip or actuate the alarm.
The features and advantages of the invention are achieved through the use of a novel non-contact switch that is shielded to prevent accidental activation as herein disclosed. In accordance with another embodiment of the present invention, a fire alarm pull station includes a housing, a non-contact switch that is located within the housing and a movable actuation device linked to the non-contact switch. The movable actuation device moves between an activation and non-activation position. A further element is an actuator protector linked to the non-contact switch. The actuator protector ensures that the non-contact switch is not activated accidentally through some external environmental condition. In the preferred embodiment, the non-contact switch is a Hall-effect switch. To enable activation of the switch, a magnet is attached to the movable actuation lever. The magnet creates a magnetic field, which causes a Hall voltage to activate the switch.
The actuator protector, when incorporating the use of a Hall effect switch, uses similar magnetic fields. The similar fields prevent an outside magnetic field from activating the device accidentally. In the preferred embodiment, the actuator protector and the non-contact switch merge into one device called a biased operation Hall effect switch.
In another aspect of the invention, a manually operated activation lever is replaced with a push button switch. The switch operates to activate the Hall switch through the creation of a magnetic field.
In another embodiment of the invention, a method is provided for actuating a fire alarm pull station in an alarm system. The method includes the steps of shielding a non-contact switch from accidental activation, sensing the movement of a movable actuation device by the non-contact switch into an actuation position and alerting predetermined sequence in response to the actuation position. A further step in this alternate embodiment is deactivating the switch upon resetting the alarm system. As an example in a push-button activation switch, the magnet is removed from the proximity of the Hall switch to deactivate the magnetic field as well as the Hall voltage.
In the step of sensing the movement of a movable actuation device, the alternate embodiment includes moving an actuation device into an actuation position, creating a magnetic field by placing the actuation device into the actuation position and supplying a voltage to the non-contact switch.
In yet another embodiment of the invention, an apparatus for actuating a fire alarm pull station in an alarm system, including means for shielding a means for switching from accidental activation, means for sensing the movement of a movable, means for actuating by the means for switching into an actuation position and means for alerting a predetermined sequence in response to the actuation position.
In a further aspect of this alternate embodiment, means for sensing the movement of a movable actuation device comprises means for moving an actuation device into an actuation position, means for creating a magnetic field by placing the actuation device into the actuation position and means for supplying a voltage to the non-contact switch.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.